For both domestic and international flights, Spirit Airlines charges passengers $45 at the gate for a bag that cannot fit under the seat. Bags that can fit under the seat are not subject to charges. Bags larger than 22 by 18 by 10 inches must be checked at the gate. The airline charges $30 for larger carry-on bags if the person bought the ticket online or over the phone, and $20 for members of the airlines' "Fare Club" who purchase their tickets online.
Spirit also charges for checked baggage, and the charges increase for each bag checked. A passenger checking three bags must pay $85 for the third bag on a domestic flight.
Large amounts of luggage are costly to airlines. According to a 2010 study by the airline analyst firm SITA, after airlines made an effort to reduce the number of checked bags on planes in 2008, the U.S. airline industry saved $94 million due to fewer lost or damaged bags.
